.COB File Extension
What is a COB file?
Source code file written in COBOL, an older programming language used for developing business, finance, and administrative applications; still used by many enterprise business applications.
COBOL has several variants, including COBOL-68 (the original standard) and COBOL 2002, a more recent version of the language. Therefore, make sure you have the appropriate compiler and text editor for the version of COBOL you're using for development.